Low-voltage equipment, and in particular low-voltage automatic circuit breakers and isolating or disconnecting switches are devices for protection and control, used generally in industrial electrical systems characterized by operating voltages of up to 1000 V. Automatic circuit breakers basically differ from isolating or disconnecting switches by the presence in the former of a device, the so-called protection relay, which controls the currents flowing in the device and supply the loads positioned downstream thereof, and brings about opening of the circuit in the event of failure or danger. To facilitate reading of the description and for sake of conciseness in the following we shall refer to the apparatuses thus designated as circuit breakers and disconnectors.
Moreover, various optional accessories that may provide circuit breakers and disconnectors with additional characteristics and functions are known in the art. Amongst such accessories it is possible for example to cite the following:    relays for remote-controlled opening of the circuit (shunt-opening relays, or SORs);    solenoids or motor-driven controls for opening and closing the switch and resetting the switch or circuit breaker;    solenoids for opening the circuit of residual-current devices (RCDs);    relays for remote-controlled closing of the circuit, (shunt-closing relays, or SCRs);    so-called minimum-voltage protection relays, for protection against lowering or absence of voltage (under-voltage relays, or UVRs); and    auxiliary contacts that supply indications on the state of the circuit breaker (open, closed, tripped).
The above accessories may be installed exclusively on circuit breakers and disconnectors pre-arranged for being equipped therewith. Furthermore, for the operation of these accessories, it is necessary to equip them with appropriate auxiliary electrical supply circuits or circuits for signal transmission. The commands and signals corresponding to these accessories are transmitted to and received from the parts of the electrical system belonging thereto by means of appropriate cables and terminals, which, in the known art, are in various ways located outside the circuit breaker or disconnector.
In the current state of the art, the solutions for connection of these electrical circuits for auxiliary supply or for transmission of the signal to other parts of the electrical system, albeit enabling provision of the required functions, present certain drawbacks and critical factors.
In particular, a first solution of a known type envisages making these connections by means of simple cables that projects outside the circuit breaker or disconnector directly from the accessory from which they derive, traversing in various ways the internal and external parts of the apparatus. It is clear that in these conditions interference of various kinds may occur between the cables and the electrical or mechanical parts that are located in the proximity of the path. This solution, which presents the cables outside the circuit breaker in the form of small bundles, entails the need for each cable to be characterized by specific markings to enable its identification and to prevent potential errors of connection. Frequently, these markings are subject to deterioration with the consequence of rendering the individual cables indistinguishable. This clearly has an adverse impact on the general reliability of the electrical wiring
The known solutions prove particularly complex when the aim is to transform a wiring solution from fixed to extractable or vice versa. In these cases in fact, it is almost always necessary to dismantle and reconnect the accessories or even replace the means of connection thereof, such as for example sockets and plugs. Obviously, all these aspects have negative repercussions both on the overall costs of fabrication and on the costs of use and maintenance of circuit breakers and disconnectors in general.